The following correction was printed in the Observer's For the record column, Sunday July 27 2008

In the article below we mentioned Barack Obama's pledge to withdraw US troops from Iraq 'within a year if he wins the presidential election in November'. In fact, the senator has stated that he aims for a phased withdrawal of troops in consultation with the Iraqi government within 16 months of taking office. This has been corrected.

Barack Obama, the US Democratic presidential candidate, arrived in Afghanistan yesterday, amid tight security on the first leg of his high-profile tour of war zones and foreign capitals.

The tour, aimed at boosting his foreign affairs credentials with voters at home and introducing himself to world leaders for the first time, started with visits to American troops on the front line.

On the way to Afghanistan, Obama stopped at Camp Arifjan, the main US military base in Kuwait and a major gateway for US soldiers moving into and out of Iraq.

Lieutenant Colonel Bill Nutter, a spokesman for the US military in Kuwait, said Obama 'talked to soldiers and constituents and met with senior military leaders'.

During the two-hour visit, the officers gave him an overview of operations, Nutter said.

Obama was due to meet Afghan President Hamid Karzai yesterday, after spending the afternoon visiting troops stationed near the eastern city of Jalalabad and consulting senior American army commanders at headquarters in Bagram.

Today Obama, who is travelling with staff, advisers and senior US television journalists, is expected to arrive in Baghdad for meetings with Iraqi politicians and American military chiefs. 'I look forward to seeing what the situation on the ground is,' Obama told reporters before his departure. 'I want to talk to the commanders and get a sense of what their biggest concerns are, and I want to thank our troops for the heroic work that they've been doing.'

Obama advocates ending the US combat role in Iraq by withdrawing troops at the rate of one or two combat brigades a month. But he supports increasing military commitment to Afghanistan, where Osama bin Laden is believed to be hiding along its border with Pakistan.

Obama recently chided Karzai and his government, saying it had 'not gotten out of the bunker' nor helped to organise the country and its political and security institutions.

Also on his trip itinerary is a meeting with Nouri al-Maliki, the Iraqi leader. On the campaign trail, Obama has said one benefit of withdrawing US troops is that it would push Maliki to shore up his government.

Obama, 46, who is ahead of Republican rival John McCain in most polls, but is seen as inexperienced in foreign affairs by many voters, has controversially pledged to withdraw US troops from Iraq within 16 months if he wins the presidential election in November. The plan was endorsed by Maliki in an interview published yesterday.

In Kabul, Obama's reception among ordinary Afghans was mixed. 'I'm not sure it will do any good, but it's nice to be the centre of attention. We feel like we have been forgotten a bit recently,' said Ahmedtullah Yusufzai, a 32-year-old tailor.

Obama's week-long trip will also take in Jordan and Israel before he visits Germany, France and Britain.